The present invention is directed to a tool for use in the preparation of optical fibers for connectorization, and, more particularly, to a ribbon separation tool for separating one or more optical fiber ribbons into subsets of optical fibers.
A fiber optic cable may include one or more optical fiber ribbons capable of transmitting voice, television, or computer data information. Examples of optical fiber ribbons are disclosed in U.S. Pat. Nos. 5,561,730 and 5,457,762, which are incorporated herein by reference. Optical fiber ribbons may be made by arranging a plurality of optical fibers in planar relationship, and then extruding a common matrix coating, such as a UV curable acrylate material, about the optical fibers. FIG. 1 is an enlarged cross sectional view of a conventional optical fiber ribbon C with eight optical fibers F, each fiber having a respective buffer layer B. Conventional optical fiber ribbons C may or may not have spaces between adjacent buffer layers B. Often the connectorization of optical fibers F requires ribbon C to be separated into optical fiber subsets. The respective ends of the subsets are then stripped of the common matrix coating, and buffer layers B are removed thereby exposing the optical fibers. The optical fibers are then ready for connectorization.
FIGS. 2 and 3 illustrate a known, all-metallic ribbon separation tool 1 used for separating a single optical fiber ribbon into optical fiber subsets. Ribbon separation tool 1 comprises a housing 2 mounting a reciprocal member 3 formed of many parts. Reciprocal member 3 is moveable along a line of action L when a pressing force is applied to a button 5. Ribbon receiving slots 4 are arranged to receive a single optical fiber ribbon C. Reciprocal member 3 includes blades 6 fastened thereto, which blades are designed to shear optical fiber ribbon C in a shearing stroke of reciprocal member 3. Cooperating with and hingedly mounted to the housing base is a pair of cover members 9 that are separated by a slit S. Each cover member 9 includes respective shearing blades 7 that cooperate with blades 6 to effect shearing of optical fiber ribbon C. Maintaining pressure on button 5, and at the same time pulling sheared optical fiber ribbon C to its end, results in a lengthwise separation of optical fiber ribbon C into two optical fiber subsets. Each of the two subsets has a number of optical fibers therein, for example, the two subsets include six fibers each. As best seen in FIG. 3, the length of the shearing stroke of reciprocal member 3 is adjustable by manipulating a screw 8 with a special tool, e.g., an Allen wrench.
Known ribbon separation tool 1 has several disadvantages. First, it is limited to separating but a single optical fiber ribbon C per shearing stroke, such that plural ribbons may only be separated in a time-consuming series of shearing strokes. In addition, only two subsets of optical fibers can be made by blades 6,7 per shearing stroke; if numerically different subsets of optical fibers are needed, blades 6,7 must be replaced with different sized blades that will result in numerically different subsets of optical fibers. Replacing blades 6,7 is a time consuming procedure; moreover, an expensive inventory of different sized blades 6,7 must be maintained. This is disadvantageous because making such an adjustment is a time-consuming procedure, and because a craftsman must keep such a special tool on hand to make the adjustments as needed. Furthermore, gap G, that exists between reciprocal member 3 and housing 2 and which allows space for the shearing stroke of reciprocal member 3, is exposed to the outside environment of ribbon separation tool 1. Such exposure is a problem because foreign matter may enter gap G and decrease or altogether block movement of reciprocal member 3 along its line of action L, thereby resulting in an incomplete or a non-shearing of optical fiber ribbon C. Additionally, as cover members 9 and blades 7 are separated at line S, the covers 9 may move independently of each other; consequently, blades 7 may be misaligned during the shearing stroke, possibly causing damage to optical fiber ribbon C and optical fibers F. Moreover, the shearing devices require many parts, some of which are machined metal parts, the manufacture and assembly of which is expensive and time-consuming.
An optical fiber ribbon break out tool is disclosed in U.S. Pat No. 5,926,598. The break out tool has die members formed of an aluminum material having slots with respective taperless, right-angle corners. The die members include keys that interfit with a frame. The frame has no distinct guide members for guiding the optical ribbons during the break out procedure. An alternative embodiment requires grooves cut in a stationary die that receive projections of a movable die during the ribbon break out procedure. This ribbon break out apparatus has several disadvantages. For example, the absence of a cover can subject the dies to the intrusion of foreign matter, and the aluminum material is generally not a high quality tool-grade material. The affect of the absence of guide members and/or the taperless right-angle corners on the optical ribbon during the break out procedure can result in stray fibers, fiber breakage, and/or matrix material damage including delamination of the matrix from the optical fibers.
In one aspect the invention provides a ribbon separation tool, comprising at least two shearing devices, at least one of the shearing devices being a movable shearing device operative to move in a shearing stroke relative to the other of the shearing devices; the shearing devices cooperating to define at least one shearing station comprising a shearing slot; the shearing slot comprising at least one shearing edge profile, the shearing edge profile comprising generally straight edges that approximate an arc.
In another aspect the invention provides a ribbon separation tool, comprising at least two shearing devices, at least one of the shearing devices being a movable shearing device operative to move in a shearing stroke relative to the other of the shearing devices, and at least one of the shearing devices being monolithically formed of a single piece of material; the shearing devices defining at least one shearing station comprising a respective shearing slot, at least part of the shearing slot being formed in the at least one monolithically formed shearing device, and the shearing slot comprising at least one shearing edge profile, the shearing edge profile comprising an arcuate shearing edge.
In another aspect the invention provides a ribbon separation tool, comprising at least one slot having generally parallel cutting edges for receiving an optical fiber ribbon therebetween; and guide members adjacent the slot for aligning the optical fiber ribbon with respect to the slot.
In another aspect the invention provides a method for making a shearing device for a ribbon separation tool, the method comprising the steps of: (a) burning a first blank with an electrode so that at least one shearing slot comprising a shearing edge profile is formed in the blank; and (b) adjusting the position of the electrode so that the electrode burns at least one shearing slot comprising a shearing edge profile into a second blank located adjacent the first blank.
In another aspect the invention provides a method for making a shearing device for a ribbon separation tool, the method comprising the step of: shaping a sinker electrode into a replica of two opposing shearing edge profiles; and applying the sinker electrode to a blank and burning the shearing edge profiles into the blank.
In another aspect the invention provides a method for making a shearing device for a ribbon separation tool, the method comprising the step of: introducing a moldable material into a mold and forming a shearing device having at least one shearing edge profile.